This invention relates to improvements in tooling for precision machining and more particularly, but not by way of limitation, to a removable and replaceable indexing and locating component adapted to be used with a sub-plate for the precision machining of parts.
Numerous types of locating pins are known in the prior art as operable to support a part on a machine or position a workpiece on a tooling jig. These locating pins are often used with a gage plate for setting fixtures and the like, such plates conventionally comprising a base and an accurately formed top surface with a plurality of circumferentially spaced accurately formed and located openings therein. Obviously, such a gage plate is expensive and time consuming to manufacture because each opening must be very accurately located with relation to the other openings. In addition, any changes in temperature in use may cause the gage plate to lose its accuracy.
The prior art locating pins are often of "round" and "relieved" configuration. They are often used together, mounted on a fixture a distance apart corresponding to a distance between two apertures on a workpiece. When a workpiece is placed on the locator pins the round one provides restraint in all directions and the relieved locator is so designed to provide transverse restraint only.
One commonly used prior art relieved locator pin is commonly referred to as a diamond locator, because of its essentially diamond-shaped cross section. In use, however, known prior art locator pins are subject to a number of defects. One class of locator pins are elemental in construction and provide only the most rudimentary type of locator pin. Another type is constructed of many precision machined parts which then require exact assembly and adjustment to function as a locator pin.
Commonly, locator pins of the first type include only a bushing that is press fitted into a hole in a fixture or sub-plate. A locating pin is then inserted into the bushing or is pre-inserted into the bushing prior to it being press fitted into the fixture. Such locator pins while acceptable for some applications are non-adjustable and cannot be easily replaced or interchanged with other pins as the need should arise.
Examples of the latter type of locator pins previously discussed are shown in U.S. Pat. Nos. 2,497,679; 3,158,045; and 3,286,354. Characteristically, this type of locator pin provides for a central bore to be formed in the fixture or sub-plate. A plurality of eccentrically formed sleeves are then inserted within one another and rotated until a desired orientation has been achieved to provide the desired locator hole. The sleeves are then locked into position by one or more particularly configured bolts which bear against the outer periphery of one or more of the eccentric sleeves.
The present invention provides a simple, readily manufactured locator pin that may be easily inserted into a fixture and which has a locating portion that may be easily interchanged or replaced as the need should arise.